1. Field of the Invention
In general, the present invention relates to clockworks for clocks that have an hour hand, a minute hand, and a second hand that emanate from a common hub on a clock face. More particularly, the present invention relates to the gearing assembly used within the clockwork.
2. Prior Art Description
Mechanical timepieces, in the form of clocks and watches, have been in existence for hundreds of years. In this long history, the mechanical clockworks that run the clocks have been designed in countless shapes that vary from large clock towers to small wristwatches.
Most clocks with mechanical movements rotate an hour hand and a minute hand around a clock face. Many clocks also include a second hand. Often the hour hand, the minute hand, and the second hand rotate about a common hub in the center of the clock face. Such a prior art clock configuration is shown in FIG. 1.
Referring to FIG. 1, it can be seen that the hour hand 10, the minute hand 12, and the second hand 14 are all connected to separate, but concentric posts 16, 18, 20. Each of the posts 16, 18, 20 attach to a gearbox 22 within the clock. The gearbox 22 is driven by a clock motor 24. The clock motor 24 may be an electrical motor, a spring wound motor, or a weight and pendulum motor, depending upon the design of the clock.
In prior art clock works, the hours post 16, minutes post 18, and seconds post 20 are concentric. The hours post 16 is the outer-most and shortest of the posts. Conversely, the seconds post 20 is the inner-most and tallest of the posts. The minutes post 18 is interposed between the hours post 16 and the seconds post 20. The hour hand 10 attaches to the hours post 16. Likewise, the minute hand 12 attaches to the minutes post 18 and the second hand 14 attaches to the seconds post 20. This configuration enables the second hand 14 to rotate freely above the minute hand 12 and the hour hand 10. In this manner, the second hand 14 is least likely bind with the other slower moving hands. The common prior art configuration is contained in numerous patents and commercial products and is exemplified by the clockworks shown in U.S. Pat. No. 1,797,912 to Hammond, and U.S. Pat. No. 2,432,416 to Haydon.
Although connecting the second hand to the tallest, center post is practical, it does present limitations to a clock's design. Since the area on the center post available to anchor the second hand 14 is very small, the clock is required to have a very lightweight second hand. Furthermore, the second hand often must be balanced about its attachment point. A lightweight/balanced second hand limits the torque experienced by the thin center post and prevents the center post from twisting or bending. A lightweight/balanced second hand also inhibits the second hand from drooping and eventually contacting the underlying minute hand. Since the second hand must be made with very little mass, it limits the ability of clock designers to create specialty clocks, especially decorative themed clocks, where decorative objects move with the second hand.
For example, suppose a clock designer wants to design a clock with a racing car theme where a racecar is attached to the second hand of the clock. The clock designer may want the racecar to ride upon the clock face and circle the clock face every minute. Using a conventional prior art clockwork mechanism, such a clock cannot be made functional. The mass of the car would be too much for the second hand to bear. This would cause the second hand and/or the post of the second hand to bend. Additionally, the clockworks do not provide the seconds post the torque needed to rotate any object of significant mass. Furthermore, the racecar cannot ride upon the clock face because it would contact the underlying hour hand and minute hand.
A need therefore exists for a clockwork mechanism that bypasses the design limitations of clockworks with conventional second hands, therein enabling more complex, interesting and artistic clocks to be built. This need is met by the present invention as described and claimed below.